DHA and EPA omega-3 fatty acids cut risk for age-related macular degeneration

Specifically, a high intake of long-chain omega-3 polyunsaturated fatty acids relative to low intake reduces the risk of developing both overall AMD and advanced AMD, with corresponding odds ratios of 0.67 and 0.60.

“In future large-scale prospective studies, cross-sectional studies, or randomized controlled trials, more attention should be paid to the association of various intake levels of different FAs with the development and progression of intermediate AMD, to avoid the occurrence of advanced AMD as far as possible,” wrote Qing Zhou, researcher at The First Affiliated Hospital of Jinan University, Guangzhou, China, and colleagues In Frontiers in Nutrition​.

They added: “Attention should also be paid to the association between AMD and the study population, dietary habits, and health awareness of the participants, and adjustments should be made accordingly, as this will greatly affect the study results.”

Fatty acids to take on AMD​

AMD is the fourth leading cause of blindness worldwide and mainly affects adults over 55 years of age, said the researchers. While there are several effective drugs in the market, patient compliance is often reduced by the need for frequent injections and doctor visits in addition to the potential for adverse effects such as endophthalmitis, retinal detachment, and traumatic lens injury, they added.

Fatty acids such as polyunsaturated fatty acids could tackle AMD as they have anti-inflammatory and antithrombotic properties in addition to benefits in maintaining vision, cognitive function, and glucose and lipid metabolism, they said.

However, the investigators explained that there are many types of fatty acids, complicating the issue. Additionally, they noted that “the effects of various intake levels of different fatty acid subtypes seem to be different in the development and progression of AMD, and the study results are always different among studies, making clinicians confused about how much level of intake of fatty acids can prevent and delay the development of AMD.”

Analyzing previous studies​

To clarify the issue, the researchers carried out a meta-analysis of 26 studies assessing the role of fatty acids in the development of AMD, involving a total of 241,151 participants. Eligible studies had to adequately define the different stages of AMD and examine the intake of fatty acids on the risk for different stages of AMD.

The majority of the included studies were carried out in the US followed by geographies including Australia, Japan and Europe. Participants in the studies reported their dietary fat intake based on the Food Frequency Questionnaire (FFQ) in 25 studies and via the Brief Self-administered Diet History Questionnaire (BDHQ) in one study.

Zhou et al found that a high intake of one of the main omega-3 polyunsaturated fatty acids, DHA, cut the risk of overall AMD, intermediate and advanced AMD with odds ratios of 0.80, 0.83 and 0.68 respectively. The investigators found a similar pattern with another main omega-3 fatty acid called EPA, with high intake cutting the risk of overall AMD with an odds ratio of 0.91 and advanced AMD with an odds ratio of 0.85.

Meanwhile, Zhou and colleagues found that the risk of overall AMD was unaffected by high and low intake levels of total fat, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, and omega-6. They also observed that increased intake of trans-fatty acids increased the risk for advanced AMD, with an odds ratio of 2.05.

Commenting independently, Harry Rice, V.P., Regulatory & Scientific Affairs at Global Organization for EPA and DHA Omega-3s (GOED), told NutraIngredients​ that the study has some limitations and that the results suggest that “further research is warranted, but limited conclusions can be drawn at the present time.”

He added: “As an aside, I do think that it would have been more informative if the two forms (dry versus wet) of AMD had been considered separately given that they are associated with different pathophysiological mechanisms. This means that there could be different effects of EPA/DHA on the development and progression between the two forms.”

A past phase 3 trial called VITAL (Vitamin D and Omega-3 Trial) failed to demonstrate a benefit of less than one gram/day of EPA/DHA for AMD incidence or progression, though subgroup analyses suggested a potential benefit, Rice observed. “For this reason, I think additional randomized clinical trials in healthy individuals with dosages greater than 1 gram/day of EPA+DHA need to be conducted,” he added.

Source: Front. Nutr​ 2024, 11:1403987

doi: https://doi.org/10.3389/fnut.2024.1403987

“Association between fatty acid intake and age-related macular degeneration: a meta-analysis”

Authors: Yan Lee et al.